Method of making an integral pinion and inner bearing race for rack and pinion assembly

ABSTRACT

A method of making a forged integral pinion and bearing seat member, especially suited for rack and pinion steering gear assemblies, which has a cylindrical body with longitudinally spaced radially projecting flanges or collars, gear teeth between the flanges, and bearing raceways adjacent the outboard sides of the flanges. The one-piece member eliminates the necessity for inner bearing rings, and the gear teeth are conveniently formed by a die rolling operation, with the dies sinking into the cylindrical body portion between the flanges for about one-half of the tooth depth to displace metal outwardly to form the tips of the teeth.

Uted States Patent Goldsmith Sept. 5, 1972 [54] METHOD OF MAKING ANINTEGRAL PINION INNER BEARING RACE FOR RACK AND PINION ASSEMBLY 2'11Appl. No.: 83,344

Related U.S. Application Data [62] Division of Ser. No. 839,420, July 7,1969,

abandoned.

[52] U.S. Cl ..29/159.2, 74/498 [51] Int. Cl ..B21d 53/28, B2lh 5/00,B2lr l/30,

B23p 15/14, 829d 15/00 [58] Field of Search ..29/ 159.2; 74/498, 496,422,

[56] References Cited UNITED STATES PATENTS 1,474,516 11/1923 Eicher..72/374 1,998,108 4/1935 Walsher ..29/l59.2 X 2,464,658 3/1949 Stivin..219/154 3,346,937 10/ 1967 Folkerts ..29/ 159.2 3,362,059 1/1968DiPonio et a1 ..29/407 X 3,362,248 1/ 1968 Meyers ..74/500 3,421,387l/l969 Adams ..74/498 3,531,976 10/1970 Fuhmlan ..29/l59.2 X

FOREIGN PATENTS OR APPLICATIONS 699,856 12/ 1 964 Canada ..74/498Primary Examiner-John F. Campbell Assistant Examiner-Victor A. DiPalmaAtt0meyl-lill, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A methodof making a forged integral pinion and bearing seat member, especiallysuited for rack and pinion steering gear assemblies, which has acylindrical body with longitudinally spaced radially projecting flangesor collars, gear teeth between the flanges, and bearing racewaysadjacent the outboard sides of the flanges. The one-piece membereliminates the necessity for inner bearing rings, and the gear teeth areconveniently formed by a die rolling operation, with the dies sinkinginto the cylindrical body portion between the flanges for about one-halfof the tooth depth to displace metal outwardly to form the tips of theteeth.

2Claims,5DrawingFigures METHOD OF l"- AN INTEGRAL PINION AND INNER BEil' G RACE FOR RACK AND BACKGROUND OF THE INVENTION 1. Field of theInvention This invention pertains to methods of making pinionstructures, and particularly pinions which have their own bearingraceways and are useful in rack and pinion devices of the typeincorporated in steering gear assemblies.

2. Description of the Prior Art Pinions for rack and pinion steeringgear have been heretofore rotatably mounted in a pair of axially spacedanti-friction bearings, each of which comprises an inner race carried bythe pinion and an outer race carried by the pinion housing. An exampleof such a rack and pinion device is shown in the prior art in theFrederick John Adams US. Pat. No. 3,421,387, granted Jan. 14, 1969. Thepinion teeth of such prior art devices were produced by machine cuttingrequiring a cutter run-out extending beyond the effective length of theteeth, requiring careful alignment and seating of the inner bearing racerings on the pinion after the cutting operation.

SUMMARY OF THE INVENTION The present invention now eliminates therequirement for separate bearing raceways to rotatably mount a pinionand provides die-formed pinion teeth between radial flanges which willstraddle the rack bar. The pinion is thus a one-piece member,inexpensively formed and providing its own raceways for anti-frictionbearing elements.

While the invention will be hereinafter specifically described asembodied in a method of making a rack and pinion assembly for automotivesteering gear, it will be understood that the principles of thisinvention are generally applicable to pinions for any usage.

It is then an object of this invention to provide a method of making aone-piece pinion and bearing raceway.

Other objects, features and advantages of this invention will be readilyapparent from the following description of the preferred embodimentthereof, taken in conjunction with the accompanying drawing, althoughvariations and modifications may be effected without departing from thespirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinalcross-sectional view with parts, in elevation, of a prior art rack andpinion device for a steering gear;

FIG. 2 is a view similar to FIG. 1, but illustrating the rack and piniondevice with the pinion and integral bearing seats made by the method ofthis invention;

FIG. 3 is a fragmentary transverse cross-sectional view taken along theline III-III of FIG. 2;

FIG. 4 is an enlarged elevational view of a forged blank from which theintegral pinion and bearing seatings of this invention are formed;

FIG. 5 is a view similar to FIG. 4, but illustrating the finishedintegral pinion and bearing seats.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 the rack and piniondevice includes a rack bar 1 which is adapted to move through a housing2. The rack bar 1 is provided with a rack 3 the teeth of which engagewith the teeth of a pinion 4. The pinion 4 is rotatably mounted inbearings shown generally at 5 and 6 in the housing 2 so that duringrotation thereof the rack bar 1 moves through the housing. The bearingassemblies 5 and 6 are axially spaced and located adjacent each end ofthe pinion teeth so that axial restraining forces are applied by thebearing assemblies on the pinion 4 which forces are directed from onebearing assembly towards the other. As shown, each of the bearingassemblies comprises an inner race seating 7 of annular form which isprovided on an annular bearing member 7a secured to, and co-axial with,the pinion 4, an opposed outer race seating 8 of annular form which isprovided on a bearing member 8a which is co-axial with the pinion 4 andis carried by the housing 2 and a plurality of balls 9 which areretained between the opposed seating surfaces 7 and 8 and movable aroundthe annular track formed by the seating surfaces. The manner in whichthe pinion 4 is rotatably mounted in FIG. 1 is well known in the art butto provide a complete construction for a rack and pinion device, therack 1 is shown slidably supported on a carrier member 10. The carriermember 10 abuts the rack bar 1 on the side thereof remote from its rack3 and is slidably mounted in the housing 2 and springloaded relative tothe housing to provide support for the rack bar and to bias the teeth ofthe rack into engagement with the teeth of the pinion.

It will be apparent that the necessity for manufacturing and securingthe bearing members 7a for the inner race seatings 7 to the pinion addsconsiderably to cost.

The teeth of the pinion 4 in FIG. 1 are usually produced by a hobbing ortooth-generating operation, both of which require a cutter run-out whichextends beyond the effective axial length of the teeth, as shown indotted lines. Consequently, the bearing members and 8a have to beapplied and secured to the pinion after the teeth-cutting operation iscompleted, or otherwise they would be damaged by the cutting process.

According to the present invention there is provided a method of makingan integral metal pinion and inner race seatings for mounting in ball orroller bearings which comprises a pinion having radially flanged coaxialinner race seatings at each end of, and adjacent, the teeth of thepinion, the flanges being of larger diameter than the diameter betweenthe roots of the pinion teeth. If required the flanges can abut the endsof the pinion teeth. Conveniently the mean diameter of the inner raceseatings is approximately equal to the diameter of the pinion teeth.

By the present invention the integral flanges are located adjacent thepinion teeth and consequently the teeth cannot be formed by a normalcutting operation since this would result in damage to the flanges.While a construction can be envisaged in which the flanges are axiallyspaced from the ends of the pinion teeth to provide sufficient clearanceto permit over-run from the ends of the teeth during the cuttingoperation without damage to the flanges, such a construction wouldnecessitate a pinion of considerably increased length which would inturn increase the size of the pinion housing (as for example in a rackand pinion device) with a resultant increase in bulk and cost.

A According to the present invention there is provided a method ofmaking an integral pinion and inner race seatings which includes forminga pinion blank having a cylindrical part the axial length of which is tocorrespond to the axial length of the toothed section of the pinion tobe made and having radially flanged, coaxial inner race seatings locatedat each end of, and adjacent the cylindrical part, the flanges being oflarger diameter than the diameter between the roots of the teeth of thepinion to be made and subjecting the cylindrical part of the pinionblank to a rolling operation between toothed dies which are appliedthereto under pressure to form teeth in the cylindrical which extend forsubstantially the axial length of the cylindrical part. Preferably thediameter of the cylindrical part of the pinion blank is approximatelyequal to the mean diameter between the roots and tips of the teeth ofthe pinion which is to be made and the rolling operation is controlledso that the teeth of the dies sink into the cylindrical part of thepinion blank for approximately half their depth of tooth and thematerial thus displaced is forced outwards to fill the cavities at theroots of the teeth of the dies to form the outer portions (or tips) ofthe teeth on the pinion.

By the method of the present invention the axial length of the teeth onthe pinion as formed from the pinion blank can be very closelycontrolled and any run-out (if at all present at the ends of the pinionteeth) is negligible.

In the rack and pinion device of FIGS. 2 and 3, parts identical withparts shown in FIG. 1 have been marked with the same reference numerals,and perform the same functions as in the prior art device of FIG. 1.However, as shown in FIGS. 2 and 3, the integral pinion and inner raceseatings unit of this invention comprises a pinion 1 l, co-axially fromwhich extends a shaft 12.

Integrally formed and co-axial with the metal pinion l1 and shaft 12 area pair of axially spaced, radially flanged, inner race seatings 13 whichare located one at, and adjacent, each end of the axial length of thepinion teeth. The race seatings 13 are intended for mounting in ball orroller bearings. The diameter of the flanges 13a for the inner raceseatings is larger than the diameter between the roots of the teeth inthe pinion 1 1 and, in the present example, the diameter of the flanges13a, is larger than the diameter of the teeth of the pinion 1 l.Conveniently the main diameter of the inner race seatings 13 isapproximately equal to the diameter of the teeth in the pinion 1 1.

The teeth of the pinion 11 in FIGS. 2 and 3 are formed by subjecting aforged metal pinion blank shown in FIG. 4 to a rolling operation. Thepinion blank is integrally formed to include the shaft 12, the pair ofaxially spaced inner race seatings 13 having the radially extendingflanges 13a and a cylindrical part 14 the axiall n of hich bt tall oreso d to the axial le nfii of tile teeth to 1?? orriieii i n tli e pirfion 11. The diameter of the cylindrical part 14 is approximatelyequal to the mean diameter between the roots and the tips of the teethin the pinion 1 1.

The cylindrical part 14 of the pinion blank is subjected to a rollingoperation between toothed dies the teeth of which sink under pressureinto the cylindrical part. The pressure of the dies is so arranged thattheir teeth sink into the cylindrical part 14 for half their depth andthe material displaced by the teeth of the dies is forced outwards intothe cavities at the root of the teeth of the dies and the displacedmaterial forms the outer portion of the teeth in the pinion l 1.

After the rolling operation the pinion can be clean ed up in knownmanner and any additional machining performed.

What I claim is:

l. The method of making an integral pinion and bearing seat member forrack and pinion steering gear assemblies which has bearing seat flangesof larger diameter than the diameter between the roots of the pinionteeth and has the pinion teeth extending closely adjacent the flangeswhich comprises forging a metal pinion blank with axially separatedflanges, an axially elongated cylindrical portion between said flangesof less diameter than the flanges and diverging at the ends thereof tothe peripheries of the flanges, inner ball race bearing seatingsconverging from the outboard ends of the flanges to cylindrical portionsand a cylindrical shaft of smaller diameter than said cylindricalseatings extending axially from one seating, subJecting the cylindricalpart of the blank between the flanges to a rolling pressing operationbetween tooth dies forming axial teeth in the cylindrical part extendingfor the axial length thereof to the divergent ends thereof, andcontrolling the diameter of the elongated cylindrical portion and theflanges so the diameter between the roots of the teeth will be smallerthan the diameter of the flanges.

2. The method of claim 1 wherein the diameter of the elongatedcylindrical portion is controlled to a diameter approximately equal tothe mean diameter between the roots and tips of the teeth and therolling pressure is controlled to sink the teeth of the dies into saidcylindrical portion about half the depth of the die teeth.

1. The method of making an integral pInion and bearing seat member forrack and pinion steering gear assemblies which has bearing seat flangesof larger diameter than the diameter between the roots of the pinionteeth and has the pinion teeth extending closely adjacent the flangeswhich comprises forging a metal pinion blank with axially separatedflanges, an axially elongated cylindrical portion between said flangesof less diameter than the flanges and diverging at the ends thereof tothe peripheries of the flanges, inner ball race bearing seatingsconverging from the outboard ends of the flanges to cylindrical portionsand a cylindrical shaft of smaller diameter than said cylindricalseatings extending axially from one seating, subJecting the cylindricalpart of the blank between the flanges to a rolling pressing operationbetween tooth dies forming axial teeth in the cylindrical part extendingfor the axial length thereof to the divergent ends thereof, andcontrolling the diameter of the elongated cylindrical portion and theflanges so the diameter between the roots of the teeth will be smallerthan the diameter of the flanges.
 2. The method of claim 1 wherein thediameter of the elongated cylindrical portion is controlled to adiameter approximately equal to the mean diameter between the roots andtips of the teeth and the rolling pressure is controlled to sink theteeth of the dies into said cylindrical portion about half the depth ofthe die teeth.